Opening the Door to Lightweighting Closures
Eco-friendly designs that are cost-effective are becoming less and less of an oxymoron.
Based on customer demand for cost cutbacks, closure manufacturers have developed lightweighted closures that reduce the amount of resin needed, and ultimately cut down on freight costs. Here's the green lining: the less resin, the less harmful materials in the waste stream, and the more closures that fit within the weight limit for secondary packaging and shipments, the fewer the shipments and the less gas guzzled in deliveries.
Lightweighted closures are a win-win in their most natural form, and many manufacturers are already making sustainable strides.
On the marketLightweighting has been a constant topic of discussion for the past few years according to John Grainda, global marketing manager for carbonated beverages with Alcoa. As much as sustainability is something Alcoa incorporates into its closure design and manufacturing practices, Grainda says it’s the demand of the major soft drink producers that’s been driving the innovation.
Alcoa is working on an entire line of short height closures called the “mini,” to be introduced throughout 2008. One of the first products in the line, the Xtra-Lok Mini, has already been launched. The 28 millimeter two-piece (lined) short height closure for soft drink bottlers offers a 12% material weight reduction from other 28mm standard-size closures.
To create the Xtra-Lok Mini, Alcoa’s design team took the weight out of the shell rather than the liner; the liner is part of the integral sealing technology and would present a whole host of problems if changed. To maintain the seal integrity, Alcoa incorporated its XT sealing liner designed to perform in extreme temperature conditions and maximize carbon retention for soft drink bottlers.
While specific cost savings are tricky to project, Grainda says making the conversion from a standard size to short height closure represents about 900 pounds of resin saved per day in a typical large-scale soft drink bottling operation.
“I think lightweighting is inherent in the design process of a performance product,” he says. “You always try to seek something lighter, stronger and yet less expensive.”
Based on the primary market it serves, Portola Packaging has been doing lightweighting for years.
“If you look at the dairy segment, you’ll find very lightweight closures to begin with; mostly just plug styles with very few liners,” says Roy Robinson, Portola’s VP of strategic marketing.
The dairy market has been moving to screw caps over the past few years, Robinson says, so Portola recently released the 38mm DBJ lightweighted screw cap. The closure is roughly a half-gram lighter than other 38mm screw caps found in the juice or isotonic category. (See the “Projected savings” sidebar below for the possible materials saved in a realistic manufacturing environment.)
Seaquist Closures recently cut out 20% of the weight per closure for its 33-400 and 38-400 ultra pour spouts. The reduction was achieved by uniformly thinning out the plastic throughout the closure. Seaquist also developed snap-on finish tube top closures for the personal care market that are inherently lighter weight than the threaded versions commonly used in the market. Performance characteristics have been maintained throughout the design process.
“It’s an understanding of market expectations, performing the necessary tests and putting in the time and resources on research and design before bringing something to market,” says DeAnn Umland, product manager for personal care and household at Seaquist. “From a company-wide perspective, sustainability and creating that awareness has been pushed to the forefront.”
While sustainability is a company objective, Susan DeGroot, Seaquist’s product manager for food and beverage, says the Wal-Mart Scorecard has been a big driver for development.
“Customers approach the scorecard differently,” DeGroot says. “Some may care more about the weight of the closure; others might care more about the level of energy used to develop the closure.”
Sonoco has also been pushing past plastics to other lightweight options. The company has reduced metal thickness by 10% on many of its metal closures and is working toward further reduction. Sonoco also offers peelable foil membrane closures that are significantly lighter in weight than traditional ring-pull easy-open (EZO) ends. The closures work with both processed and non-processed foods.
ChallengesSo if lightweighting closures reduces materials and shipping costs, why haven’t manufacturers done it all along?
Unfortunately, the technology isn’t as simple as making the closure thinner with less plastic resin. As the weights are reduced, the material chemistry requirements become more critical to meet manufacturing, functionality and application requirements. To improve consumer opening performance, Alcoa designers created a new “SureGrip” knurl design that resembles a classic crown appearance.
“You have to make sure you can still apply the closure at very high speeds, with the closure and sealing system integrated with the capping support equipment, all as efficiently and productively as possible,” Grainda says.
The lightweighted short height closures also still have to perform at the same quality levels in variable filling conditions. According to Grainda, designing a lightweighted closure with a sealing liner that would perform in extreme hot and cold filling conditions, not to mention shipping and distribution conditions, was a challenge. Malt beverage operations present different capping considerations than aseptic beverages, for example.
Unfortunately, the exact design characteristics incorporated to retain the same level of quality, if not a higher one, are trade secrets.
With cost savings at the forefront, customers want to make sure the lightweighted caps can run on pre-existing lines. In most cases, the machines require minor retoolings, if any change is necessary.
“We’ve had to make sure that our customers’ capping equipment can handle the closures and make sure that the thread profiles of the bottle match up,” Robinson says about Portola’s lightweight options. In some cases, bottle threads need to be changed and some minor tooling changes were needed. But Portola has a tooling group within the company to facilitate these changes as efficiently and cost-effectively as possible.
Alcoa’s Xtra-Lok Mini Closures can be applied with machinery from all capping equipment manufacturers.
Above and beyondFor some manufacturers, commitments to sustainability extend beyond lightweighting. Employees at Seaquist have formed internal groups called Green Teams that look at further ways of reducing the company’s impact on the environment. The teams are in the beginning stages of exploring the viability of using corn- and soy-based resins for closures.
“We’re in the plastics business, so we should be looking at what we can do better,” DeGroot says. “We’re putting a focused, concentrated effort behind this. Being environmentally responsible is one of our top priorities.”
Sonoco is also switching its solvent-based compounds to water-based compounds and coatings, both reducing materials costs and improving sustainability efforts.
Portola, too, is looking into corn-based resins for future closures, but Robinson says the prices are still too high for large-scale production. While many consumer packaged goods companies are forming social responsibility platforms and making strides to be more environmentally conscious, cutting down on costs is still their biggest challenge.
Until the costs drop low enough, Portola will focus on finding other processes that could allow for further lightweighting.
“It’s all about process rather than material,” Robinson says.
For more information:Alcoa Closure Systems International Inc.
Portola Packaging Inc.
Projected savingsWhile a cost-savings analysis is dependent on too many external factors to create a realistic number, a little math can go a long way in materials savings. Here's a savings projection based on Portola Packaging's 38mm DBJ hot-fill plug:
Average amount of material saved per closure: 0.5 grams
Typical closure order from average manufacturer: 100 million closures
100 million closures x 0.5 grams per closure = 50 million grams saved per order
50 million grams saved is roughly 100,000 pounds of resin saved
The short listHere’s an at-a-glance look at weight reduction efforts:
Sonoco -10% reduction with metal closures
Alcoa -12% material reduction with the Xtra-Lok Mini plastic closures
Seaquist -20% reduction in Ultra Pour plastic spouts
Portola -15% reduction in screw caps